1. Field of the Invention
The present invention relates to a perpendicular magnetic recording head and a perpendicular magnetic recording/reproducing head that records information on a medium surface of a recording medium by applying a magnetic field in a direction perpendicular to the medium surface.
2. Description of the Related Art
A general perpendicular magnetic recording head has a layered structure including a main magnetic pole layer and a return yoke layer that are arranged so as to face each other with a nonmagnetic insulating layer interposed therebetween along a surface that faces a recording medium (medium-facing surface). The main magnetic pole layer and the return yoke layer are magnetically connected to each other at a position spaced from the medium-facing surface in a height direction. A coil layer for generating a recording magnetic field between the main magnetic pole layer and the return yoke layer is embedded in the nonmagnetic insulating layer. In this type of magnetic recording head, when electricity is applied to the coil layer, a recording magnetic field is induced between the main magnetic pole layer and the return yoke layer. The magnetic flux of the recording magnetic field extends from the medium-facing surface of the main magnetic pole layer, enters a hard layer of the recoding medium in a direction perpendicular thereto, passes through a soft layer of the recording medium, and returns to the return yoke layer. Thus, information is recorded on the recording medium in an area facing the main magnetic pole layer (refer to, for example, U.S. Patent Application Publication No. 2005/0083608(A1)).
On the other hand, a general perpendicular magnetic recording/reproducing head includes a reading unit including a lower shield layer and an upper shield layer. The lower shield layer is formed on a nonmagnetic insulating layer that is provided on a slider, and an upper shield layer is formed so as to face the upper shield layer with an inorganic insulating layer (gap insulating layer) interposed therebetween. A read element is disposed in the inorganic insulating layer.
In the perpendicular magnetic recording head and the perpendicular magnetic recording/reproducing head, the return yoke layer and the shield layers are generally formed of substantially rectangular magnetic thin films. Accordingly, when an external magnetic field is applied in the height direction, the magnetic flux concentrates at the edges of the magnetic films. At this time, of the magnetic field components in the magnetization directions, a component in the height direction becomes the largest, which leads to overwriting of existing information (edge writing). In order to reduce the edge-write magnetic field, it is necessary to reduce the magnetic field component in the height direction that are generated at the edges of the return yoke layer and the shield layers.